Polyvinyl butyral sheeting has been used for many years as an interlayer for glass laminates. When such laminates are subjected to an impact sufficient to fracture the glass sheets, the interlayer absorbs the energy of impact and prevents the shattering of the laminate.
A major application for these safety glass laminates is automotive windshields. In this application, it is generally desired to print a tinted gradient band on the polyvinyl butyral interlayer. For compatability with the interlayer, a printing ink is often used which is based on solvent, polyvinyl butyral and the desired dyes. A particularly satisfactory printing technique is described in Moynihan, U.S. Pat. No. 3,591,406.
With the use of such printing inks, it has been found that the tinted gradient band tends to adhere to adjacent sheeting during handling. In addition to this problem, known as blocking, adhesion of the tinted gradient band to the glass in finished laminates is less than the adhesion of the unprinted portion. This results in imperfections in glass laminates prepared from the sheeting.